As system on chip designs become more prevalent, analog circuitry, e.g., radio frequency transceiver circuitry, is more frequently being placed on the same chips as digital circuitry, e.g., digital signal processing circuitry. While this type of design has many benefits, such as compactness of design, challenges arise in preventing electrical noise from one type of circuitry interfering with the operation of the other type of circuitry. This noise coupling is often in the context of noise from the digital circuitry interfering with the operation of the analog circuitry. Noise coupling is becoming more and more critical as the speeds of digital circuitry continue to increase.
FIG. 1 illustrates a conventional electrical coupling of digital circuitry 10 and analog circuitry 14 with one another via an analog-to digital converter 18. While each of digital and analog circuitries 10, 14 are connected to separate respective power distribution networks 22, 24, these circuitries share a common ground network 28. Conventional technologies, such as deep trench and voltage island technologies (not shown), provide high substrate impedance between the digital and analog circuitries 10, 14 for isolating the noise. However, these technologies do not inhibit noise coupling through ground network 28 that is common to both the digital and analog circuitries 10, 14. What is needed is a solution that inhibits noise coupling between digital and analog circuitries 10, 14, yet permits signals to pass between these circuitries with high fidelity without pulse width distortion.